If you really want to see some very dramatic effects, I have some from KH6
where it was absolutely imperative to do HFTA.
Going south up a 13500 ft mountain I was on, even plotting with a 2000 ft
tower it was impossible to get any lobes below 6 degrees. However, to the
north I looked down into a 400 ft ravine across the street which gave me 9
or so dBi gain on 80 meters.
Unless you live in southern FL or the KS plains, HFTA is really helpful.
Bill K4XS/KH7XS
In a message dated 3/2/2012 6:51:05 A.M. Greenwich Standard Time,
dotravel@aol.com writes:
Unless you are on totally flat ground for miles around you'll need to run
the Microdem program to import your exact location into HFTA to actually
get the correct gain and take off/landing angle info along with the predicted
historic DX angles that work.
Without knowing how your local terrain affects the theroetical antenna
height you won't have much to go by!
I can send you some examples of my QTH if you'd like -- tribander at 50'
with a 225' drop-off to the East. .
John NA6L
-----Original Message-----
From: Bob K6UJ <k6uj@pacbell.net>
To: Towertalk <towertalk@contesting.com>
Sent: Thu, Mar 1, 2012 4:46 pm
Subject: [TowerTalk] 15 meter yagi height for 6000 miles
Has anyone used the HFTA program and can tell me the best height for a 15
meter
yagi for 6000 miles.
Assuming there aren't any hills obscuring the take off angle.
The carribean is about 6000 miles from my qth and from experimenting I
have
noticed that lowering the beam
down from 90 feet down to 50 feet it is markedly better for 15 meters.
I just bought the new antenna handbook and plan to dive in and learn how
to do
the HFTA myself but was
hoping someone else had an idea of the best take off angle angle for 6000
miles
on 15.
I believe 50 feet is about 3/4 wavelength high and gives me a 20 degree
takeoff
angle on 15.
Hope this all makes sense, hihi.
Bob
K6UJ
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